Questions & Answers about Bomba je u starom vozilu.
Je is the 3rd person singular form of the verb biti (to be).
So:
- bomba = subject
- je = is
- u starom vozilu = prepositional phrase
Croatian usually needs the verb to be in this kind of present-tense sentence, just like English does:
- Bomba je u starom vozilu. = The bomb is in the old vehicle.
You generally cannot leave je out here.
Because the preposition u changes meaning depending on the case that follows it.
Here it expresses location (in, inside), so it takes the locative case:
- u starom vozilu = in the old vehicle
If it expressed movement into something, Croatian would normally use the accusative instead:
- u staro vozilo = into the old vehicle
So the form tells you whether the phrase is about being somewhere or moving somewhere.